After over 7 years of Use
This lens is a great travel lens. It works wonderfully with my 40d and 5d. While not the sharpest lens in my bag it is more than adequate for travel and snap shots. The image stabilization does it jobs and I can shoot hand held with out issue--I do bump up the ISO when necessary just because I like fast shutter speeds. I have not experienced the lens slippage mentioned so much in the other reviews. However, having read about the lens slippage issue several years ago--I do not push and pull on the barrel at all (as I don't want the lens to start slipping). The build quality to me is very good and the quality of contrast/sharpness is acceptable. The best way to tell if this lens will meet your needs is to head your local camera store for some test shots with your camera and review/pixel peak if you like at home. Also, if slippage is a concern inspect the lens at the store --turn it facing down--that will tell you a story. I really like my 28-135mm and based on my experience--I can recommend this as a very good travel lens.
January 1, 2014

Excellent add to cabag
At first the lens challenged the areas that I wanted to shoot in. After a few minutes of toying with the lens and my settings in the camera I was able to learn to fully manipulate the lens to my advantage as well as my cameras advantage. The image quality in low light seemed to be an issue but proved to be user error and was easily overcome after a few shots and setting adjustments. The images are sharp and far far from soft as some have said but that is my experience with the lens and my experience shooting as well. Facial features on tight and close ups are absolutely amazing, super sharp and super tight. It has proven to be a great buy and I would not only suggest it as a great weapon in the arsenal in your bag but as a must have the macro and well as it being a great all around 18-135. Just amazing It would have been perfect if the lens did not slide with the downward angling of the camera to adjust to that you have to learn to hold it to keep the focus not a big deal only when you don't remember and it slides and the shot is off
November 18, 2013

much sample variation
I bought this EF 28-135mm last year as a general purpose lens for my 5D. it turned out to be a bad sample and the right side of the frame was soft, yet the center and left were sharp. I sold it and tried another one at a camera shop(made in Taiwan) this was uniform but the edges were low resolution and dark. The sales person took one off of a used 7D kit, this one was Made in Japan and it was much better (sharp right to the edges) and no falloff,I bought it.
It turns out that it was serviced and aligned by Canon. Unless yours was serviced by Canon-Who knows..
October 17, 2013

Barrel Slide
My comment is specifically addressing an issue I have with the Canon 28-135mm lens with Image Stabilizer, AF/MF, and Macro functions. I have been a Professional Photographer for over 20 years and I am happy with the image quality in the photo's I've taken, however when taking pictures on even the slightest downward angle the barrel starts sliding causing the image to be out of focus. This is very frustrating to say the very least, especially when I'm hired to take pictures at a Live Event where I may only get one shot at a high point moment and I find the picture out of focus because of the barrel slide issue. At the end of the day when I sort through pictures for the most exciting shots and have to delete many because the lens barrel was sliding, I feel that I let the client down because I didn't give them a complete set of pictures that represented the entire event. I had checked comment posting reviews about this lens and the number one main issue that kept reappearing again and again was the "barrel sliding" issue. As far as recommending this specific lens, I can't do so with a clear conscience because I wouldn't want someone else to end up disappointed because of the barrel slide issue. I do hope that Canon will address and correct the barrel slide problem. All of my camera's and many of my lens's are Canon and I am very happy and satisfied with their performance. I have and will continue to recommend Canon products.
October 8, 2013